1. Field of the Invention
The present invention relates to a low temperature co-fired ceramic material, a low temperature co-fired ceramic body, and a multilayer ceramic substrate. More particularly, the invention relates to improvements for suppressing variation in sinterability of a low temperature co-fired ceramic material.
2. Description of the Related Art
A SiO2—BaO—Al2O3-based low temperature co-fired ceramic material is known as an electrical insulation material used for multilayer ceramic substrates. This material can be co-fired with a metal material that has low resistivity, such as copper, and has high insulation resistance and a low dielectric constant, thus being useful, in particular, as a substrate material used for electronic component modules for radio frequency applications.
In order to improve various properties, additives are added to the SiO2—BaO—Al2O3-based low temperature co-fired ceramic material. For example, as disclosed in Japanese Unexamined Patent Application Publication No. 2004-345928 (Patent Document 1) and Japanese Unexamined Patent Application Publication No. 2008-44829 (Patent Document 2), Zr may be added thereto as an additive.
It is disclosed in paragraph [0029], etc. of Patent Document 1 that, by adding an appropriate amount of zirconium, a dense ceramic sintered body having good sinterability and a high Q value can be obtained. Furthermore, it is disclosed in paragraph [0074], etc. of Patent Document 2 that, by adding an appropriate amount of zirconium, a high bending strength and a high Qf value can be obtained.
However, the SiO2—BaO—Al2O3-based low temperature co-fired ceramic material has a problem in that, in particular, when multilayer ceramic substrates are industrially manufactured using this ceramic material as a raw material, a variation in quality (in particular, sinterability) easily occurs between raw material lots.